Grid for an electron discharge device



y 1936- c. H. GREEN 2,048,502 I GRID FOR AN ELECTRON DISCHARGE DEVICE Filed June 25, 1932 4 '3 4 H H oo J 2o FIG. .4 j j j; 30

O O O O O O O O O O O O Y O 0 0 FIG. I o o c I7 18 I2 l3 FIG. 3

INVENTOR CECIL H. GREEN BY'eK ATTOR EY Patented July 21, 1936 f UNITED STATES PAI'T-IENT OFFICE GRID FOR AN ELECTRON nIscnARGE DEVICE Cecil H. Green, Newark, J., assignor to International Communications Laboratories, 1110.,

Newark, N. J.,,a corporation oi New York Application June 25, 1932, Serial No. 619,307

' Claims. (01. 250-215) struction of a grid member which is substantial .andwhich will retainits position and form when subjected to intense heat during the operation of the electron device.

According to my invention-the .grid, which is preferably cylindrical .in shape, is formed by crossing a plurality of wires, preferably of :molybdenum, and twisting the wires together at the intersections or crossings so as to form a rigid screen or mesh. The wires'at one endjof the cylindrical screen are interwoven with openings in a base, or support, at the time the screen is being formed. Wires suitable-for grid construction whenspot-welded become brittle and are easily subject to breakage- Forming the grid with the wires twisted together at the intersections, or crossings, overcomes this defect and produces a rugged type screen which is not readily broken even with rough usage.

The method of making the grid according to my invention will be explained in the detailed description to follow:

Fig. 1 shows complete grid structure;

Fig. 2 shows a sectionthrough the mandrel from which the grid is formed;

Fig. 3 shows a portion of the mandrel;

Fig. 4 shows the first stage in construction of the grid in a developed form;

Fig. 5 shows a section of the grid in a developed form;

Fig. 6 shows an enlarged explanatory diagram of Fig. 5; and

Fig. '7 shows the manner in which the wires are twisted together.

Referring to Fig. 1, the grid, as shown at 25, comprises a screen or mesh formed by interweaving a plurality of wires in the manner to be explained later.

The grid wires are looped through, or interwoven with, the ring-shaped base 20. The supporting prongs 22, 23 and 24 attached to the ring are fastened to the base of the tube (not shown) in any manner well known in the art.

Referring to Figs. 2 and 3, a mandrel 30 is provided with a series of openings into which pins II to I8 are inserted. These pins fit snugly within the openings and are removable at will. One end of the mandrel is provided with the reduced portion 3| which fits within the ring support 20 when the wires arebeing interwoven with one another.

In starting the formation of the screen, or mesh, the first set of pins is inserted in the lower set ofv openings extending around the circumference of the mandrel 30,as shown in Figs. 1,

- Inthev present instancejI have illustrated "a .screen'formed of four lengths of wire made into loops and threaded through the openings 2I in 10 the ring 20, thus providing eight wires, I to 8, extending vertically, as shown in Fig. 4. After this operation the end 3| of the mandrel is inserted into the ring 20 and positioned so that the wires pass to the left of pins II to I8. The upper ends of the wires I to 8 may be attached to a temporary securing or holding device fastened to the upper end of the mandrel 30 to retain them .in position.

In forming the grid, .wire I is first turned to the right over pins II and I2 and twisted with wire 2 at pin I2, as shown in Figs; 5, 6 and 7.

Fig. 7 shows in detail the form of twist used. After the twist is made, wire 2 is again placed in a vertical position, as shown, and wire I is then turned to the right over pin I3 and twisted with wire 3. Wire 3 is then placed in a vertical position and wire I continues on and is twisted with the remaining wires 4 to 8 in the same manner, after which it is looped with itself at pin II, as shown in Fig. 6; after which it is placed in a vertical position.

It will be noted that wire I is twisted with each wire at its respective pin in the lower set.

After this operation, a second set of pins is inserted in the second set of openings in the mandrel 30 and all of the wires which are now in a vertical position pass to the right of their respective pins in the second set.

Wire 2 is now turned to the left over pin I2 in the second set, then over pin II in the second set and twisted with wire I, after which wire I is placed in a vertical position.

Wire 2 is now turned over pin I8 and twisted with wire 8, after which wire 8 is placed in a vertical position. This action is continued until wire 2 is twisted with each wire at its respective pin, after which it is looped with itself and placed in a vertical position.

A third set of pins is now inserted in the third row or set of openings in the mandrel, after which wire 3 is turned tothe right over pin I5 in the third row, then over pin I 4 and twisted with wire 4.

' This operation is continued until wire 3 is 5 .third'. row or set.

From the foregoing it will be noted that each of the wires, I to' 8, will completely encircle the mandrel at a certain row of pins, and will be twisted with all of the wires during theencircling operation; 7

The grid may be extendedto any desired by continuing the interweaving of the wires in,

the manner described. The size and shape. of the openings in the mesh, or screen, are determined by the position of theopeninzsin the mandrel within whichthe pins are inserted.

In Figs. 5 and 6 the arrowsindicate the direction the wires take duringth'e formation opera tion; Fig. 6, for cleamess, showsthencircling wires without twists. v V V After the grid has been interwoven togive desired length, the ends are interwoven' to form a reinforcing ring- 26, as shown in Fig. L'a'fter which the loose or surplus ends are :cut oil. the foregoing it will 'be' seen that thegridlis rigid and substantial and is only supported by the base 20 with which it is interwoven. It is unnecessary to a support for As is ,common practice, well known in-the art,

the fllamen t is positioned within the grid and the anode is positionedto; surround" the grid. The

grid made according to my invention not buckle or bulge to' come in contact with the filament or anode when heated during the operation of the electron discharge device. 7

What is claimed is: i

1. A grid electrode composed only of a plurality'of turns of wire spaced apart by at least three peripherally spaced longitudinalwires intersectingandlintertw-ined said turns at the points of intersection, each longitudinal wire being con-- tinuous with a plurality of said turns, andsuccessive turns serially included in the same longitudinal wire being 'separated'by a number'of mg tubular electrode.

wire. being separated by turnssfonned' in V 2,048,502 Y twisted with each 'wire atits respective pin in the turns corresponding to the number oflongitudi- 4 nal wires. 7 r

2. A grid electrode composed only of a tubular base and a plurality of wires secured thereto and extending from one edge thereof in a direction v 8 we. andv "af plurality of wires secured'thereto and extending from one edge thereof in a direction parallel to the axis thereof; and each of said wires. 7 at apoint intermediate its ends extending periphextally to fonn a turn intersecting the longitudinal wires and fastened thereto at the points of intersection, said turns being spaced longitudinally of. said wires thereby to form a self-support o r 4; A grid electrode composed only of aitubular base and a plurality of wires secured thereto and extending from one edge thereof in a direction parallelto the axis thereofiand each of said wires at each-of a phn'alityof spaced points mtermeits ends. extendmg perlpherally t form turns mtersecting 'said wires and fastened thereto at theintersectingpolnts, successive. turns m others of said wires. w t 5. A grid electrod' only ofthreefor :more wires positioned syamnetncally'abwta com- ;mon axis and extending substantially parallel thereto',.each wireat a plurality of spaced points 7 intermediate its-ends having form edtherein parssuer intersecting said longitudinal wires and intertwined therewith atth'e points-p1 intersection, successive turnsin each wire bemgsepa- 'rated by parallel turns: in others of. said} wires whereby pp r in cylmdncai grid ele'etrode'is formed; r

. 4 cEcmn. GREEm- 

